Novel Materials Laboratory

Department of Physics

Department of Chemistry

Division of Materials Science and Engineering

Angle Resolved Photoemission Spectroscopy

Hemispherical electron energy analyzer

Sample

E_F =            Fermi energy

E_vac =          Vacuum level

E_i , k_i=        initial energy and momentum of electron in solid

E_f , k_f =       final energy and momentum of electron following excitation

E, k =         energy and momentum of free electron in vacuum after emission

F =             E_vac – E_F = work function

hn  =           incident photon energy

 

Energy conservation gives E(k) = hn – F – E_i(k_i)

Momentum conservation parallel to the surface gives:

 

 

 

 

 

 

Momentum is not conserved perpendicular to the surface, but for a given inner potential V₀, we can write:

 

By measuring the kinetic energy (E) and momentum (k) of the electron in vacuum, the dispersion of the electron state E(k) in the solid can be determined